—No. Teachers always warn us ________ in the river because it's very dangerous.
A:no swimming
B:don't swim
C:not swim
D:not to swim
2×0.7与0.2×7的结果相同,意义也相同。
去年暑假,小梦陪着爷爷到湖里叉鱼.小梦将钢叉向看到鱼的方向投掷,总是叉不到鱼.如图所示的四幅光路图中,能正确说明叉不到鱼的原因是( )
阅读漫画,回答问题。