Scientists have to work hard to keep ________ with modern discoveries and developments.

29．“It is not who you know but what you know that_______，if you want to find a job in this company．”he said angrily．

Sam remembered several occasions in the past ______ he had experienced a similar feeling [ ]

It has been cold and windy recently. If only it ______sunny and clear now!

ngwrong with it, ______—No. Yours is a specially-built model. Drivecarefully, though.