Scientists are warning that ________ emissions of carbon (碳排放) are cut, we could be heading for an environmental disaster.
A．before B．as
C． unless D．in case
——Did you inform Helen of the plan put forward at the meeting?
—Of course. ________ I saw her.
A．So long as B．If only
C．The moment D．Any time
Please call my secretary to arrange a meeting this afternoon, or ________ it is convenient to you.
A．whenever B．however
C．whichever D．wherever
She usually keeps her valuables, such as jewels and money, ________ she believes secure.
A．even ifB．in case
C．whereD．that
How can they expect to learn anything ________ they never listen?
A.whetherB．when
C．butD．unless
—I wonder how much you charge for your services.
—The first two are free ________ the third costs $30.
A．while B．until
C．when D．before
