下列各组字母中全部是元音字母的是 ____。A. a, e, o, r B. a, i, u, e C. o, u, e, n
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 ________.