5. I'm sorry he's busy now.
恐怕他现在没时间接您的电话。
还能这样说：
I'm afraid he's occupied now.
I'm sorry he is tied up.
应用解析：
You are busy as a bee from morning to night.
你真忙！
6. His line is busy at the moment.
他正在通话。
还能这样说：
He's talking on another line.
He's on another line now.
应用解析：
at the last moment 在最后关头；
at the moment 此刻，那时；
every moment 时时刻刻；
for a moment 片刻；
in a moment 一会儿、不久，立即、马上
7. When will she be back?
她什么时候回来？
还能这样说：
How long do you think she'll be back?
Do you know what time she'll be back?
谚语：
What is got over the devil's back is spent under his belly.
（钱财）来得不正，去得也不正。
8. She should be back after lunch.
她午饭后应该会回来。
还能这样说：
The time she can be back is after lunch.
It is after lunch that she should be back.
应用解析：
at the back of one's mind 在记忆的深处，下意识地；
at sb.'s back 跟随某人，支持某人；
be glad to see the back of 希望摆脱某人；
be laid on one's back 卧病在床