Who is the man ____ (你刚才在操场和他握手)?

He built a telescope ____ he could study the skies in his free time.

Thetimehascome_____wemakeextensiveuseofnuclearenergy.

Heborrowedabooktheotherday，theauthor____isaworker.

Maria:Doyouthinkyouwillgetapayrisenextyear?

Leo:______.