下列有关热现象的说法中正确的是（　　）

用现代汉语给下列句子中的划线词作注释。

①居____数月，其马将____胡骏马而归。（《塞翁失马》）

②策____之不以其道，食____之不能尽其材，鸣之而不能通其意。（《马说》）、

③一鼓作____气，再____而衰，三而竭。（《曹刿论战》）

    Today is Friday. Peter has six classes today. He goes to school at 7:30 a.m. At 8:00 a.m., he begins his first class. The first class is English. At 9:00 a.m., he has math. Peter likes math because it’s interesting. At 10:00 a.m. she has a biology class. Peter thinks it's very boring. Then at 11:00 a.m., he has a history class. That's his favorite subject. He can learn a lot about the past from history.
    Peter has lunch at school at about 12:00. Then he has a short break. At 1:30 p.m., he has a music class. At 2:30 p.m., he has a P.E. class. Peter likes this afternoon, because music and P.E. are easy and interesting. School is over at 4:00 p.m. Peter is happy because he can go home and have a good time on Saturday and Sunday.
阅读短文内容，选择正确答案。

下列命题中正确的命题个数为（   ）
①若直线则直线a∥,
②若直线上有无数个点不在内则∥
③若直线∥则与内的任意一条直线都平行 
④如果两条平行线中的一条与一个平面平行，那么另一条与这个平面也
平行
⑤平行于同一个平面的两条直线可以相交

边长3分米的正方形,周长是（   ）