A:水在任何温度下都能汽化
B:水结冰时要吸收热量
C:水的比热容比沙石、干泥土比热容大得多,这是沿海地区昼夜温差较小的主要原因
D:随着社会的发展和人口的增长水资源已出现严重危机,我们一定要节约用水
画一个比直角小的角
A. He is sending an email to his friend.
B. This dress is for Amy.
C. The boys are playing football.
D. This girl is writing a letter.
E. We had a happy time in the park.
(____)
(____)
做匀速圆周运动的物体,改变的物理量是( )
你知道影子是怎么形成的吗?