题目

据报道，科学家已成功合成了少量的O4，有关O4的说法正确的是  （    ）A．O4的摩尔质量是64 g                            B．O4与O2互为同位素 C．相同质量的O4与O3所含原子个数之比为1∶1       D．O4与O3．O2都是氧元素的同分异构体  答案：C解析:略  The patient was in bad need of operation but there was no guarantee(保证) that she would survive the anaesthetic (麻醉剂), which made the doctors on the horn of a __________.A．processB．arrangementC．ceremonyD．dilemma