________ this cake, you'll need 2 eggs, 175 g sugar and 175 g flour．
A．Having made B．Make C．To make D．Making
Although the causes of cancer ________, we do not yet have any practical way to prevent it．
A．have uncovered B．have been uncovering
C．are uncovering D．are being uncovered
Someone who lacks staying power and perseverance is unlikely to _________ a good researcher．
A．make B．turn C．get D．grow
They _________ two free tickets to Canada, otherwise they'd never have been able to afford to go．
A．had got B．got C．have got D．get
—Have you been wasting time on computer games again?
—________．I've been studying a lot and I need a break．
A．No way B．Not really C．I don't agree D．I couldn't agree more
________ walk is expected to last all day, so bring ________ packed lunch．
A．A ; a B．The; 不填 C．The; a D．A ; 不填
