第17题: [单项选择]He hopes he can visit the United Nations building while he ____________ in New York next summer. A. has been B. is C. will be D. shall be 参考答案:B 答案解析:状语从句。他希望明年夏天在纽约市能够参观联合国大厦。▲在由if,even if,as, when,as soon as,until,till,after,before,whenever,while等词