-- Mr Smith ,What shall we do next? -- Let students ___________for discussion.
It was found that although the girl could perceive things with her fingers, this ability ceased _____ her hands were wet.
______ you understand this rule, you’ll have no further difficulty.
It will not be long _____man can harness the solar energy and make it serve mankind.
Doing your homework is a sure way to improve your test scores, and this is especially true______ it comes to the classroom tests.
Substances will expand or contract ______ heated or cooled, but this is not the case with water.