哪些铁路乘车证可以免于签证?
参考答案:
以下铁路乘车证可以免于签证:
⑴全年定期乘车证、
⑵通勤乘车证、
⑶通学乘车证、
⑷定期通勤乘车证、
⑸就医乘车证、
⑹购粮乘车证、
⑺便乘证。
— David has gone to Australia on business.
— Really? I ______ why he was absent from today's meeting.[ ]
A. am wondering
B. wonder
C. was wondering
D. had wondered
为什么掺活性混合材料数量多的硅酸盐水泥(如矿渣水泥)比硅酸盐水泥适合高温护?