玩具进行跌落测试时,撞击面应达到肖氏硬度()
A.A50度±5度
B.A60度±6度
C.A70度±7度
D.A80度±10度
参考答案:D
Our classroom by us every day!
A.is cleaning
B.has cleaned
C.must clean
D.is cleaned
In the Great Depression, the American government couldn’t find good solutions _____ the unemployment problem.
A.of
B.to
C.on
D.about