My friend David was not used _______ by air, so he felt unwell(不舒服).
We are waiting until the weather ________ a little.
--He must have received a good education in his childhood, ________ he? --________, he is polite and well-behaved and acts like a gentleman.
An increasing number of countries have been ________ China as a threatening power recently.
All the citizens here strongly insist those found ________ “harmful” advertisement in the streets ________ punished strictly.
Scientists are convinced ________ the positive effect of laughter ________ physical and mental health.