关于高分子化合物叙述不正确的是（）。
A. 分子质量很大
B. 分子链很长远大于其分子直径
C. 化学组成也比较复杂
D. 由相同的结构单元重复而成
An oil in water monitor is required in order to measure （）.
A. the oil content in water
B. the water content in fuel oil
C. the water level in bilge well
D. the oil level in bilge well
Ryan was late for the conference yesterday （） the traffic jam.
A. because
B. since
C. for
D. because of
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