书名：疾天阅读满分2 1000题
版本：2017.2再刷 实测01
页数：p.22~26
题目：
>>第1题<since用在过去完成>
Guest will be allowed to enter the venue two hours ____ the performance starts.
(B)before
(D)since
疑问：答案为B，什么时候才用since ?
>>第18题 <正确答案为D，之前对错答案>
Operating the up-to-date equipment at the factory demands a high level of
technical ____.
(C)facility
(D)expertise
疑问：没事了
>>第19题<正确答案为C，之前对错答案>
For being the worker who ____ most positively, Eliza received a small cash
bomus.
(B)have evaluated
(C)was evaluated
疑问：没事了
>>第35题<specialize +in 特殊用法>
The city's public healthcare workers ____ in providing treatment for the
elderly.
(C)specialize
(D)guarantee
疑问：答案为C，为何D不行?
>>第41题<非分词构句(动词只有一个)也非关系代名词(不会有逗点)，逗点后直接加过
去式动词(礼拜一)>
June 8 - At a press conference on Monday, Amanda Doolittle, the event director
for Blackridge County Fair, ____ that pop sensation Max Avery will be giving
a perfomance on the final night of the fair.
(A)confirming
(C)confirmed
疑问：答案为C，为何不是A，逗点后面who confirmed省略who动词加ing? 还有再问一个
这个时候逗点后要用关系代名词，who指Amanda，which指Blackridge County Fair
，两种用法都可以吗?
共5题，烦请能人解