Food shortage will long be a worldwide problem _______ much has been done to supply enough for everyone.
| A．before | B．if |
| C．since | D．although |
Look at the timetable. Hurry up!! Flight 4026 _____ off at 18:20.
| A．takes | B．took | C．will be taken | D．has taken |
Ladies and gentlemen. Please fasten your seat belts. The plane _________.
| A．takes off | B． is taking off | C．has taken off | D．took off |
We saw _____farms which were built more than a hundred years ago.
| A．abandoned | B．abandon | C．abandoning | D．to abandon |
She explains English grammar ___clearly _____even I can understand it.
| A．even…if… | B．so…that… | C．as…if… | D．but…and… |
The school year is divided into two semesters, __________is September through December.
| A．the first of which | B．the first of them |
| C．the first of it | D．the first of that |