鼻导管低流量（3L／min）给氧，FiO₂可达（）

A.24%

B.28%

C.32%

D.36%

E.40%

There was a woman in Detroit, who had two sons. She was worried about them, especially the younger one, Ben, because he was not doing well in school. Boys in his class played jokes on him because he seemed so (21) The mother (22) that she would help her sons to do (23) in school by herself. She told them to go to the Detroit Public Library to (24) a book a week and do a book report for her.
One day, in Ben’s class, the teacher held up a rock and asked (25) anyone knew it. Ben put up his hand and the teacher let him (26) . "Why did Ben raise his hand" all of his (27) whispered (耳语) and wondered. "He (28) said anything. What could he possibly want to say" To their surprise, Ben not only (29) the rock, but also said a lot about it. He (30) other rocks in its group and even knew (31) the teacher had found it. The teacher and the other students were (32) Ben had learned this from doing one of his book (33) .
Later Ben became the (34) student of his class. When he finished high school, he went to Yale University and (34) became one of the best doctors in the United States.

Ⅱ. 完形填空

A．classmates

B．students

C．teachers

D．friends