Question

he began to work THERE( ) A.on his fifty B.at age of fifty C.when he fifty D.in his fifties

说原因

Answer 1

D
on his fifty 没这种说法，应该是on his fifties,在50多岁的时候
at age of fifty,是说50岁那一年，强调这一年的事
when he fifty，应该是when he was fifty
in his fifties，是在50多岁的时候开始在这工作的

Answer 2

D他五十来岁的时候就在这工作了
A没有这个词组
B词组错误 at the age of fifty的话就可以选
C从句缺少系动词，若when he was fifty就对了

Answer 3

表示某人几十岁时用in+one's+整十数基数词的复数形式来表示，所以选D