15, Airline tickets are very expensive. If they(be)....... cheap, I(fly)......... to Singapore
16, Iam very tired tonight. If I (not be)..........tired, I (go)......... to the movie with you
18, It isn't Saturday. If it (be).......... Saturday, I (go).......... to the beach
17, I don't have enough time. If I (have)........... enough time, I (go)........ to the park
19, I have to go to class today. If I (not have to)........ go to class today, I (go).......shopping or (visit).......... my friend
20, I don't understand that sentnces. If I (understand).......... that sentences, I (explain)....... it to you
21, If I (know)...... that you were ill last week, I (go).......... to see you
22, Tom (not enter)....... for the examination if he (know)...... that it would be so difficult
23, Paul got to the station in time. If he (miss).......the train, he (be).......... latr for his interview
24, It's good that Mary reminded me anout Daisy's Birthday. I (forget)..........if she (not remind)..........
25, The weather was bad. We (go)................camping if the weather (not be)...... so bad
26, I (send).............. you a postcard while I was on holiday if I (have)........your address
27, You (have)......... a good time if you (be)................ at the party last night
28, I didn't know it was your birthday. I (get).....you a present if I (know)...... it was your birthday