650. in step 步伐一致; out of step 步伐不齐

649. stare at 目不转睛地看, 凝视, 盯着

648. take a stand against 采取某种立场反对 take a stand for 采取某种立场支持…

647. on the pot(=at the place of the action)在现场, 在出事地点; 或(=at once) 立即

646. in spite of (=despite) 尽管

645. specialize in 专门研究, 专攻

644. speak ill of 说…的坏话; speak well of 说…的好话

643. be sorry about/for 懊悔的,后悔的,难过的

642. smell of 有…的气味

641. on the sly (=secretly) 偷偷地