1. They isn't a cloud in the sky, but it (be) cloudy in the morning a) is
b) was
c)were
2. Mrs. Clay usually finishes her work at half past three, but she (finish) it later yesterday afternoon.
a) finish
b) finishes
c) finished

There isn't a cloud in the sky, but it was cloudy in the morning.  (c)Mrs Clay usually finishes her work at half past three, but she finished it later yesterday afternoon.  (c)

1. b)

2. c)

Объяснение:

в past simple в утвердительной форме к глаголам ставятся окончания -d -ed, а к прилагательным и существительным, например, ставятся слова was/were