银行汇票的实际结算金额不得更改，更改实际结算金额的银行汇票无效。( )
参考答案：对
解析： 本题考点是银行汇票兑付的基本规定。
机体的内环境指的是
A．体液
B．细胞内液
C．细胞外液
D．细胞内液+细胞外液
E．血液
We _________ the work on time without your help. [ ]
A. hadn't had finished
B. didn't have finished
C. couldn't have finished
D. can't have finished
