化学支撑科技,促进我国航天事业迅速发展。在飞船的火箭推进器中常装有液态肼[N2H4]和过氧化氢[H2O2],它们混合时的反应方程式为:2H2O2+N2H4═N2+4X,则下列说法正确的是
Sally, I heard you're going to America. Will you stay there?
Two whole years.( )
How soon
How often
How long
Wow…another gift! What's in the box?
I'm not sure. It be a pair of sports shoes.( )
must
may
will
A smile costs _________,but gives so much.So we should learn to smile.( )
something
anything
nothing
everything
I got up early this morning my grandma at the airport.( )
to pick up
picking up
picked up
Who is boy playing soccer over there?
He is my classmate, Li Ping.( )
a
不填
the