一个收购站收购花生,第一天收购了1800千克,第二天收购了2100千克,第三天收购3000千克,平均每天收购多少千克?
(1800+2100+3000)÷3=2300(千克)
在例行日交割交收方式中,交割交收的时间是由证券公司和投资者商定的。( )
Substances will expand or contract ______ heated or cooled, but this is not the case with water.
A.when they will be
B.if they will be
C.as they being
D.when