1. Walking, running, rollerblading, swimming, dancing, and jumping jacks are all forms of aerobic activity. 散步、跑步、滑旱冰、游泳、跳舞和跳伞都是有氧运动的形式。
2. Several moments went by, one of the big Jacks pawed at the ground with his hooves and another looked behind him, as if to check the rear for a surprise attack. 过了好一会儿，其中一只大公驴用蹄子刨地，另一只回头望向他，似乎在检查后面那只是否会突然袭击。
3. The main-beams of the lower deck had to be shored with screw-jacks forthwith. 下层甲板的主梁必须立即用螺旋千斤顶进行支撑。
