铸造支托在基牙缘处的厚度为
A.0.5~1.0mm
B.1.0~1.5mm
C.1.5~2.0mm
D.2.0~2.5mm
E.2.5~3.0mm
参考答案:B
My sister has a lot of trouble ______ maths. [ ]
A. to learn
B. learn
C. learns
D. learning
π的值是3.14,它是一个有限小数.______.(判断对错)