利他行为
参考答案：
利他行为是指生物所做的有利于其它生物的事情。这种行为有可能自己也是受益者，有可能只是他人能够受益的作为。
It is reported that large amounts of money spent on the bridge so far.
A．was
B．has been
C．were
D．have been
It was _____ and hot all day.[ ]
A. sunny
B. sun
C. suny
