混凝土的强度等级是按照什么来划分的？
参考答案：立方体抗压强度标准值
用动词的适当形式填空。
1. He wants _______ (swim) in the pool.
2. He likes _______ (run ) in the morning.
3. They often go ______( see ) an action movie.
4. School usually ______(start) at 8:30 am and ______ (finish) at 4:30 pm.
5. Please ______( fill ) in the blanks.
A．+→
B．→+
C．+→
D．→+
pm.
+
→
→
+
+
→
→
+
