I think you should work harder ________ you are satisfied with the way things are.
A．if B．when
C．since D．unless
．Ram explained to his mother ________ he would get home late that night because of extra work.
A．that B．which
C．what D．whether
Air pollution is getting more and more serious, so we must take action ________ it is too late.
A．before B．after
C．until D．when
Sarah Brightman, ________ will fly to space in 2015, is the first woman to fly there in the field of music.
A．who B．that
C．which D．whose
(2013·江西十所重点中学二模)The businessman wears a suit and a tie with a beard ________ the season.
A．whatever B．wherever
C．whenever D．however
(2013·陕西宝鸡二检)The course about Chinese food attracts over 100 students per year, ________ up to half are from overseas.
A．in which B．for whom
C．with which D．of whom
