This river has changed its course many times. It _________ always located where it ________ at present.
Sometimes proper answers are not far to seek ______ food safety problems.
To get a better grade, you should ______ the notes again before the test.
I ______ through that bitter period without your generous help.
Even the best writers sometimes find themselves _____ for words.
The island, _____ to the mainland by a bridge, is easy to go to.