The Cambrian . . . . . . . . an important moment in the history of life on earth and a time of radical evolutionary experimentation when many animals first . . . . . . . . in the fossil record.

Identify the tense used in the following sentence:
I have been working on the problem.

A. Present Continuous

B. Present Perfect Continuous

C. Past Perfect

D. Past Continuous

Identify the tense used in the following sentence:
They will have been writing their letters.

A. Future Perfect Continuous

B. Future Continuous

C. Present Perfect Continuous

D. Present Perfect

Identify the tense used in the following sentence:
I will represent him in court.

A. Simple Present

B. Simple Future

C. Simple Past

D. Future Continuous

Identify the tense used in the following sentence:
I will give him a gift.

A. Simple Present

B. Simple Past

C. Present Continuous

D. Simple Future