________ the river is polluted, it will take years to become safe and clear again.
A.Once B.Although C.Until D.Unless
A true friend can see the pain in your eyes ________ everyone else believes the smile on your face.
A.while B.until C.before D.because
(2016●南通市)Jack is still working to high standards he has made great achievements.
A.until B.if C.though D.because
I was giving a phone call to my mum________ Jim asked me for help.
A.while B.before C.after D.when
________ you look after it carefully, this coat will keep you warm through the whole winter.
A.If B.Unless C.Before D.After
She is listening to music ________ Peter is doing his homework.
A.after B.before C.while D.unless
