After she_____all the greetings cards, the singer____ a short thank-you speech.

A. The possibility of changing the Martian environment

B. The challenge of interplanetary travel

C. The advantages of establishing colonies on Mars

D. The need to study Martian ecology

B. lacks

C. hopes

D. neglects

A. The work I do is harder, so I get better grades.

B. I work harder than before even if I get better grades.

C. The harder I work, the better grades I get.

D. The work I do is better, so I work harder.

A. appealing

B. committed

C. specialized

D. admitted

A. humanity

B. civilization

C. constitution

D. philosophy

A. hadn't received / moved

B. don't receive / had moved

C. didn't receive / have moved

D. haven't received/moved