13.they started off at about 5 o'clock in the morning.they should there by now .a:arrive b:have
问题描述：
13.they started off at about 5 o'clock in the morning.they should there by now .a:arrive b:have
been arriving c:have arrived d:be arriving
答
C have arrived
should have arrived表示本应该到了,按照句意他们五点就出发了,现在按道理应该到了BD是什么意思B 他们本应该正在到达D 他们应该将要到达