a teachers college 师范学院(teachers等于teachers’)
one trousers pocket 裤兜(trousers等于trousers’)
eight hours sleep 八个小时睡眠(hours等于hours’)
a three weeks training 三周训练(weeks等于weeks’)
注：eight hours sleep 之类的说法，既可表达为eight hours’ sleep，也可表达为 an eight-hour sleep。类似的如：
a five-second pause 一次五秒钟的停顿
a ten-minute break 一次十分钟的中间休息
a two-hour exam. 一次两小时的考试
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