“第一目击者”在最初数分钟内提供的________非常关键，因为这一时间段往往是救命的________。
参考答案：救护，黄金时刻
聚苯乙烯的结构为，试回答下列问题：
（1）聚苯乙烯的链节是______，单体是______．
（2）实验测得某聚苯乙烯的相对分子质量（平均值）为52000，则该高聚物的聚合度n为______．
（3）已知聚苯乙烯为线型结构的高分子化合物，试推测：______溶于CHCl3，具有______（填“热塑”或“热固”）性．
When landing a lifeboat through heavy surf with a p current running parallel to the beach (from right to left when facing from seaward) the recommended procedure is to（）.
A.approach while coming to the left to take advantage of the current
B.drop an anchor outside the surf line，then pay out anchor line over the bow while the seas carry the boat toward the beach
C.approach slow enough so that the boat can be brought around to meet breaking seas on the bow
D.rig a drogue with tripping line over the bow，back ashore with drogue tripped between breakers
，试回答下列问题：