14÷33的商保留两位小数是______,精确到千分位是______.
14÷33=0.••42,
则商保留两位小数是0.42,商保留三位小数是0.424.
用适当的介词填空。
1. How many minutes are there ______________ an hour?
2. I'll give my friend a present ______________ her birthday.
3. There are so many people ______________ China.
4. The girl asks her teacher ______________ helping.
5. We often go to school ______________ bus.
不属于红外局域网的数据传输技术是______。
A.定向光束红外传输
B.全方位红外传输
C.漫反射红外传输
D.直接序列红外传输