重点讲解：
1. sign up for
（和…）签约；雇用；报名（参加课程）；
eg. Many men sign up for the army because they can not get ordinary jobs.
由于找不到工作，许我男人都报名参了军。
eg. Her parents urged her to sign up for a computer course.
父母督促她报名参加计算机课程。
2. opposite sex
异性；
eg. These people, usually men, seem unable to relate to the opposite sex.
这些人，通常为男性，似乎不懂得如何跟异性相处。
eg. Body language can also be used to attract members of the opposite sex.
肢体语言也可以用来吸引异性的注意。
3. lose one's head
不知所措；头脑发昏；没主意；慌里慌张；
eg. He was not a man to lose his head in an emergency.
他这个人在紧急情况下是不会糊涂的。
eg. I never thought that I was gonna lose my head
我从没想过我会不知所措。
