---Why does the river smell terrible? ---Because large quantities of water .
--It’s said that no one ______ light a cigarette at a gas station. --- Yes. Safety always comes the first.
I don’t know ______ or not the books _____ to the homeless children next month are really useful.
—I failed again in the math test. -- ______.
This year __________ to be another good one for harvests.
If a web page asks for some personal information, you need to find out if the page is __________ or not.