12÷0.5=____
9.3÷0.3=____
3.6+5.4=____
6.5÷0.05=____
将左边和右边的匹配起来。
①Put up____ A. your book.
②Stand____ B. your hand.
③Open____ C. up.
地壳中含量最多的元素是( )