下列说法错误的是（　　）

A．不同分子所表现的化学性质不同

B．分子质量和体积比原子要大

C．原子的质量主要集中在原子核上

D．氦气由氦原子构成

I was reading Shirley Hazzard’s novel The Transit of Venus. Though I (51) her other books, I had always resisted this one. It (52) me as too pure somehow, too heroic, larger or finer than life and therefore unreal. But now I read it with an almost (53) pleasure. There were sentences that (54) of gratification to my eyes and (55) the hairs on the nape of my neck. I was in a Boston hospital, propped tip in bed with a feeding tube in my arm after (56) surgery for cancer. It was

(57) double room and my roommate, who (58) when he spoke because he had both a broken chin and a drug habit was spraying the air for the fourth or fifth time that day with (59) had a television set and a radio going (60) . The diagnosis of my case was ambiguous. When I asked the doctor the usual question-How much time have I got—he hesitated before answering. "I would say," he said, "that you have in the neighborhood of years.\

52().

A.stroke 

B.strike 

C.struck 

D.striking