What do you think of teaching, Bob?—I find it fun and challenging. It is a job ______ you are doing something serious but interesting.

Professor Williams keeps telling his students that the futureto the well educated. [ ]

_________ we could afford it, we wouldn’t go abroad for our holidays

It was spring _____ my mother bought me a mountain bike and I started learning cycling. [ ]

Both Li Lei and Mike are thirteen years old. Li Lei is _________Mike.