1).He began to work there____.
A. on his fifty
B. at age of fifty
C. when he fifty
D. in his fifties
2). They moved to Beijing _
A. in 1980s
B. in the 1980 '
C. in the 1980s
D. on the 1980's
3). We all like the boy__.
A. of ten years old
B. ten-year-old
C. at ten old
D. of age of ten
4).She was ___ her early twenties when shewent abroad.
A. at B. on
C. of D: in