A. boulder B. singer C. happen to D. keep cool A. development B. correctly C. angel D. Tian'anmen Square A. compare to B. gleam C. invention D. in charge A. concise B. fall off C. union D. further A. hybrid B. give birth to C. hello D. chimney A. pizza B. nearly C. production D. fairness A. nor B. serve C. circuit D. What a shame A. explorer B. dynasty C. few D. grandmother A. fight B. reference C. passage D. hockey A. invader B. aerospace C. dark D. aircraft