Choose the verb phrase in the sentences

1. I could have been entering the sixth grade already.

OPTIONS:
A. could have
B. could have been
C. could have been entering

2. The delivery worker has been ringing the doorbell.

OPTIONS:
A. has been
B. has been ringing
C. the delivery worker has been ringing
the doorbell

3. You should be helping at church.

OPTIONS:
A. you should be
B. should be helping at church
C. should be helping

4. I would have been going if possible.

OPTIONS:
A. would have been going
B. if possible
C. I would have been​