You've been a great help, I must say.
依我看，你真是帮了个大忙啊。
I must go to the bank and get some money.
我得上银行取点儿钱。
He must be 70 if he's a day!
他至少70岁了！
You must signal which way you are going to turn.
你要朝哪个方向转，必须发出信号。
You're a great help, I must say!
我得说，你可没少帮忙！