例句： I want to know if he will join us in the discussion?
例句： Don’t eat too much sugar since it is bad for your health.
例句： Scarcely had he arrived at home when it began to rain.
should+动原；were to do sth
例句：I know nothing about him except that he used to work in Shanghai.
(Because) being short of money, we can’t afford a TV set. =Because we are short of money, we can’t afford a TV set.