If steel is heavier than water, why are ships able to on the sea?( )
A.floatB.flyC.fallD.flow
_______ she's wrong,it's not a big deal.( )
A.AlthoughB.BecauseC.If
His mother won't be there,________ his father might.( )
A.andB.butC.or
_______ pleasant journey it is!( )
A.HowB.WhatC.What a
My best friend helps to ______ the best in me,as the saying goes.( )
A.bring outB.bring inC.bring up
Artemisinin _______ by Tu Youyou,a great Chinese scientist.( )
A.was inventedB.invented
C.has invented