31: he hasn't gone abroad before
32:that computer has been used for three months
33:she won't visit her friends because she does not have time
35: he asked me how much I thought it would cost
36 If it doesn't rain tomorrow, we will go camping
37:I have never traveled by air before
38the students are studying for the exam now
39:the weather was so cold that we dicided not to go out
40:the house where we is lived nowis built in the 19 th century
