Sending Sandra a letter was ________,because her husband might intercept (截取) it.
It was not until dark _____he found _____he thought was the correct way to solve the problem.
Great changes have taken place in that school, it is no longer ________ it was 20 years ago, ________ it was so poorly equipped.
The way he did it was different ______we were used to .
Some researchers believe that there is no doubt ______ a cure for AIDS will be found.
The place _______ the bridge is supposed to be built should be________the cross-river traffic is the heaviest.