"by then "用什么时态?
问题描述：
"by then "用什么时态?
答
by then用将来完成时
Be married next Christmas,for you will have got your master's degree by then.
明年圣诞结婚吧,因为到那时你已经拿到硕士学位了.
It was by then overshadowed,militarily,by Russia.
军事上,它那时已经处在俄国的下风.