2019年mpacc考试英语真题——介词和介词短语56

{01}We are flying ________ 20,000 feet．I feel very nervous．
A.at altitude of
B.at an altitude of
C.at the height of
D.at an altitude
解析：表示“在某一高度”为at an altitude of或at a height of，该名词常指各种不同高度中的某一个高度，故通常要加不定冠词，且后面要带介词of，因此，正确选项为B。
本题选B。
{02}The practice of children working in factories has nearly ________．
A.died off
B.died out
C.died
D.died down
解析：
本题选B。