tobe后面加什么词

　　It was a real struggle to be ready on time.

　　要按时做好准备确非易事。

　　There's money to be made from tourism.

　　旅游业非常有利可图。

　　You're bound to be nervous the first time.

　　第一次总是会紧张的。

　　Physics used to be very much a male domain.

　　物理学曾在很大程度上是男人的领域。

　　I like to be on my own sometimes.

　　有时候我喜欢一个人待着。