Hong Kong has about forty public beaches. Some of them are very famous around the world. People can go there for a swim. You can go to them by bus. To go to some beaches yu must take a boat.
You will swim there without danger if you remember these instructions:
?Never swim alone.
?Never go out in a boat if you cannot swim.
?Never swim after a meal or when you feel hungry or tired.
?Don’t stay in the water too long.
Remember:A red flag means that it is dangerous for anybody to go into the water.A blue flag means that it is dangerous for children.
根据短文内容，判断下列各句正误。正确的在题前括号内写“T”，错误的写“F”。
小题1:There are about 40 public beaches in Hong Kong.
小题2:You should swim after a meal.
小题3:You can take a bus to go to most of the public beaches.
小题4:You’d better swim when you’re alone.
小题5:If you were a child, you could swim when you saw a red flag.
。由两梁横截面面积相等可得：
。截面形式的变化对梁内弯矩的分布没有影响，因此M1max=M2max。两种不同截面形式下梁内最大正应力之比为：