1. It places a terrible strain on the mother-child bond by saddling the mother with the double burden of playing the role of both mother and father;
    离婚使得母亲既当母亲又当父亲而不堪重负，从而造成母子关系的紧张。

2. Their spaceship was equipped with a double door, which was fitted with a bellows between the ship and the outside.
    他们的太空飞船上装有两层门, 在这两层门之间, 即飞船与外界之间, 装有一个减压舱.

3. The Japanese spent $10.9 billion for teaching outside of regular classes last year, according to the institute, including $9 billion on jukus for students in the ninth grade or below — almost double the figure spent seven years ago.
    据该机构调查，去年日本人花在正常课堂教学之外的开支为109亿美元，其中90亿是花在课外学校，用于九年级或九年级以下的学生，这几乎是七年前的两倍。

4. His income is double hers.
    他的收入是她的两倍.

5. He suggested that a double railway-tunnel should be built.
    他提议建一条双轨隧道，

6. As is so often pointed out, knowledge is a two-edged weapon which can be used equally for good or evil.
    正像人们常常指出的，知识是一把双刃刀，可以用于造福，也可以用来为害。

7. Politicians agree, in principle, so America and the EU have been trying to reach a deal which would eliminate the need to double-test many products.
    政治家在原则上同意了， 因此，美国和欧洲一直在寻求达成协议，以便为许多产品取消双重检查。

8. Though it would be a two-edged weapon when they fought each other.
    不过，当它们相互撕打时，毒液就成了利弊参半的武器，可以杀死对方，也可以被对方的毒液杀死。