We advise parents ______ their children at home alone in order to keep them away from danger.( )
not to leave
not leave
not leaving
__________ the help of modern technology, scientists got a photo of a black hole.( )
A.AtB.InC.OnD.With
Will you stay here for dinner with us?
Sorry, I ____________. My mother is waiting for me at home.( )
A.mustn'tB.can'tC.needn'tD.couldn't
What do you think of working as a doctor?
It 's a good job to help people keep___________.( )
A.busyB.strictC.healthyD.generous
Betty has a beautiful _________. She wants to be a singer in the future.( )
A.voiceB.lookC.noiseD.sound
Oh. my God! I forgot to bring my pen here.
Don't worry. I have two. You can use __________.( )
A.IB.meC.myselfD.mine