治疗弱视的最好时机是( )
A．3岁前B．4岁前C．5岁前D．6岁前E．7岁前
参考答案：D
They went to the park yesterday, _____? [ ]
A. don't they
B. didn't they
C. aren't they
D. can't they
桥墩（台）身混凝土灌注速度不得快于（）。
A.0.5m/h
B.1.0m/h
C.1.5m/h
D.2.0m/h
