16) is starting
17) Have you met
18) are going
19) will help
20) stay (хотя можно и are staying, зависит от всего текста)
21) are going to fall
22) have been waiting
23) will go
24) works
25) has always interruptied
26) didn't meet
27) was listening
28) do yoy take
29) left
30) was watering