First... create these 3 curves (fig 19), or download this step 1 file (Right-Click Save-As), if you open this file you will have 3 curves : 1 straight curve and 3 circle curves (fig 19)

开始...创建3条曲线(fig 19),又或者在下里下载(点击右键另存为),如果你打这个文件，你将得到3条曲线: 1条笔直的曲线和3条画圈(fig 19).

OK first step, select all these curves, then select edit curves > intersect curves, you will have these 6 intersect areas, it means this operation will cut these intersect areas (fig 20). Next select back all of these curves then go to edit curves > cut curves. Now you will see some areas has been removed autmatically (fig 21)

第一步，选择所有的曲线，使用edit curves > intersect curves命令,你将在这些范围得到这6个相交点，这意味着我们将这这里剪切它们(fig 20).现在选择所有曲线并使用 edit curves > cut curves命令.现在你可以看到这些相交点自动的移动到相应位置.

But if you select them one-by-one (individualy), some of these curves are still connected (fig 22). We don't want it, cause for this operation, we need to separate all of the intersected curves.
OK now select back all these curves then go to edit curves > cut curves again, this time all of the areas has been cutted out (fig 23), ahhh...OK...this is whats we need to start.

如果最初你是一条一条的选择这些曲线，那么其中的一些曲线仍然是连接着的(fig 22).我们不想这要，我们需要分离所有的相交点.
好,再次选择所有曲线,再次使用 edit curves > cut curves,这次在所有的相交点都产生了剪切(fig 23).OK,这就是我们想要的结果.

Now select these curves (fig 24), and delete them (fig 25), now you have correct intersected areas, but they're still separated curves, we need to attach all of them right?. You cannot just select all these curves and attach them together.

现在选择这些我们不需要的曲线(fig 24),并将它们删除(fig 25).现在我们得到正确的相交区域,但是它们依然是分离的曲线,我们需要将它们以正确的方式连接起来.你不可以选择所有的曲线然后连接它们在一起，这是不对的.

OK now select these 2 curves (straightcurve first then the circle one) (fig 26), then go to edit curves > attach curves > option box and apply these settings (fig 27), these settings means we'll use connect curve attach method and remove unnecessary multiple knots.

现在选择这两条曲线(直线和其中一条弧线)(fig 26), 使用 edit curves > attach curves > option box 命令并使用这个设置选项(fig 27),这些设置表示我们用连接的方式并将不需要的插入新的相交点.

Now hit Attach, then you will have this new curve (fig 28). Next with this new curve still selected, shift-select another curve (fig 29), and press "G" (repeat command), now they're attached right? (fig 30)

点击Attach,我们得到新的曲线(fig 28).当这条曲线仍然被选择的时候,按住Shift键选择另一条曲线(fig 29),按一下"G"(快捷键--重复上一次命令),这样是否正确的连接了?(fig 30)

Now Shift-Select next separated curve and hit "G" again, repeat this steps until the last curve attached (fig 31), and don't worry about some of strange connection there, we'll fix them later.
OK. now turn on select by component type icon to see all of the CVs (fig 32). Now we'll fix these connection areas (fig 33)

再次按住shift键选择另一条线并按"G"键,重复这一步骤并将所有曲线连接(fig 31),现在不要担心其中一些奇怪的连接，我们将对它们进行修复.

现在将部件方式打开可以看到CV点(fig 32),我们将对这些区域进行修正(fig 33)

Before fixing these connection areas, something that we should know that we still have the original curves, these original curves will guide us to fix the connection areas.
OK First, we're gonna fix no 1 connection area, zoom to this no 1 area, select this CV (fig 34), drag it to the bottom a little bit (following original curve) (fig 35)

在修正这些区域之前，我们必须知道我们还有最初未连接的曲线，这些未连接的曲线将做为我们修正这些区域的参照.
我们现在修正 1 号区域, 将这一区域放大显示, 选择这个CV点(fig 34),将它向下拉一点(以未连接的曲线为参照)(fig 35)

Now select this curve (fig 36), drag it to the top near the previous curve (fig 37)

然后选择这一CV点(fig 36),并将其向上拉靠近另一CV点(fig 37)

Extremely warning while moving : Do not until touching the previous curve and do not overlapped previous curve, if you do this, then you will have crossed CVs, with crossed CVs you will have very bad extrusion, bevel, loft, and other curve surfaces, and with crossed CVs you'll be always have error messages while filleting objects, etc...so don't mess with this crossed CVs guy...baaad result eh..o_0

Ok, next do the same steps to fix another connection area, here's the sample of area no 3 (after fixed) ( fig 38). After finished with all connction areas, click select by object type button , move this final curve to another location (fig 39)

移动CV点的警告:不要尝试将两个CV点重叠或者下面的CV点超过另一CV点，如果你这样做了，那么在你作用Extrude,bevel,loft,circular fillet或者进行其它曲面操作的时候，你将得到一个很糟糕的结果

继续使用这一方法将其它区域修正,这里是第3个区域修正后(fig 38).在完成这些工作后，点击回到物体选项,将完成的曲线移动到另一位置(fig 39)

Select all of original curves, delete them all, select back your final curve and put it back to its original location (translate X = 0), then select edit curves > open/close curves to close your final curve, now you will have a cute single closed curve fig (40)

将那此用作参照的曲线删除，并将新的曲线移动回原来的位置，用edit curves > open/close curves命令将曲线闭合(fig 40)


Ok now you know the ideas right ?, it's about curve intersection, of course you could do some experiment with these intersection tool to create another complex curve. This Intersection tool always great for architectural based modeling (create basic walls, floors, etc).

OK.现在你有了正确的思维了吧？这就是曲线的相交方式，当然你可以用这种方式创建其它的复杂曲线。相交工具在基础的建筑建模方面是非常实用的.