________ nearly all behavior is learned behavior is a basic assumption ________ has been put forward by social scientists.
They kept trying _________ they must have known it was hopeless.
There are five pairs _________, but I’m at a loss which to buy.
.It’s ____ so easy as you imagine.
_________ going to the exhibition.
.______ I admit that there are still some problems about the traffic in this area, I don’t mean that it can’t be solved.