Most environmental problems exist because adequate measures for preventing them ______taken in the past.

I have no objection ______ the evening with them.A．to s...

单项选择题I have no objection ______ the evening with them.

My dog has never, ______ anyone, except when provoked.A...

单项选择题My dog has never, ______ anyone, except when provoked.

I agree with you that David is a clever guy, but I thin...

单项选择题I agree with you that David is a clever guy, but I think he ______ very foolish just now.