1.will have learnt
2.will have arrived
3.had conducted
4.have never heard
5.began
6.ran
7.had made
8.was driving
9.buys
10.are you going
11.have started
12.consists
13.are understanding
14.hasn't come
15.was switched off
16.is,stopped
17.is usually watered
18.was invented
19.have you seen
20.will have written