I have a tight budget for the trip，so I'm not going to fly ________ the airlines lower ticket prices.(2012·上海，32)
A．once B．if C．after D．unless
________，Carolina couldn't get the door open.
A．Try as she might B．As she might try
C．She might try as D．Might as she try
________ the jewels were locked in a strong box，the thieves stole them without any difficulty.
A．If B．Unless C．Although D．Because
________ he comes or not，the result will be the same.
A．Even if B．Whether C．No matter D．Although
________ volleyball is her main focus，she's also great at basketball.(2011·北京)
A．Since B．Once C．Unless D．While
________ hard you try，it is difficult to lose weight without cutting down the amount you eat.(2012·湖南)
A．However B．Whatever C．Whichever D．Whenever
