Kate is a little()than Mary.
A.younger
B.young
C.the youngest
D.youngest
参考答案:A
While Helen ________ the piano,her mother came in.
A.was playing
B.is playing
C.played
D.plays
影响角度测量成果的主要误差是()。
A.仪器误差
B.对中误差
C.目标偏误差
D.竖轴误差
E.照准个估读误差