1m检影时影光为顺动,表示()
A.>-1.00D的近视
B.≤-1.00D的近视
C.正视
D.>+1.00D的远视
E.≤+1.00D的远视
参考答案:B, C, D, E
(2013·成都一诊)Parents are doing all they ________ to help their children achieve their ambitions.
A.shall
B.can
C.may
D.need
Al-Ni二元陈化、稀硼单加有何优缺点?