在企业生产经营活动中，员工之间团结互助的基本要求是讲究合作，避免竞争。
参考答案：错
医用氧气瓶中的氧气持续释放后，瓶中氧气的质量______、体积______、密度______（选填：变大、变小、不变）．
Tom is ______ tired. He has ______ homework to do every day. [ ]
A. much too; too much
B. many too; too many
C. much too; too many
D. too many; too much
