They have leading experts in this field，and that's __________ they've made important progress．
A．whereB．why
C．whetherD．who
I've heard that preparations __________ for the coming festival．Let's give them a hand．
A．are being madeB．have been made
C．are makingD．have made
Parents often tell their children that they __________ take candy from strangers．
A．needn'tB．wouldn't
C．shouldn'tD．daren't
Careers Advice service is only available to people __________ on day-time courses．
A．to studyB．study
C．studiedD．studying
I thought it hard to complete the project at first，but I __________ my mind．
A．changeB．have changed
C．had changedD．would change
I have no doubt that he will make it，but I wonder __________ he is really ready enough．
A．whatB．why
C．whetherD．that
