一What are you going to do this weekend?一Well,we’ll clean up the city parks _______ it rains .
His grandfather ______ for twelve years.
________ you've got a headache. You drank too much last night.
In those days, books could only be produced one at a time by hand. __________, they were expensive and rare.
It is clever ________ you ________ me work out the maths problem.
There is ________ in the classroom, so we can see ________.