The rise of oil prices made scientists search for new energy resources ______ oil．
A．replace B．replacing C．to replace D．replaced
You didn't believe John won the first prize at the speech competition, ______?
A．did he B．didn't he C．did you D．didn't you
I had reached a point in my career _____ I needed to decide which way to go．
A．why B．which C．when D．where
Here are some new computer programs _____ for home buildings．
A．designing B．design C．to design D．designed
sweet and fresh, this kind of food is so popular with local people and the tourists．
A．Smell B．Smelling C．To smell D．Smelt
Always read the label ______ you wash your clothes．
A．before B．unless C．since D．until
