如图表示夏季晴朗白天植物光合速率的变化.下列分析中,不正确的是( )A.如果A.B两曲线表示不同CO2浓度下同一植物两个生理状况相同的叶片的光合速率,那么曲线A表示较高CO2浓度环境下的光合速率B.如果A.B两曲线表示相同CO2浓度下同一植物两个生理状况相同的叶片的光合速率,那么曲线A表示较强光照下的光合速率C.产生c点的主要原因是中午气温过高,抑制了酶的活性D.影响ab段和de段变化的主要限制因子都是光照强度
Every time Tom is late, he'll ___________ an excuse. So I wonder what his excuse is this time.( )
A.set upB.put upC.take upD.make up
The ____________that there is life on other planets has always encouraged scientists to explore the outer space.( )
A.invitationB.possibility
C.orderD.advice
I didn't see you at Jim's party last week.
I had to work that evening, so I _________ go.( )
A.needn'tB.mustn'tC.couldn'tD.shouldn't
The path was covered with snow,so we walked very _______.We were afraid of falling.( )
A.quicklyB.carefullyC.excitedlyD.hurriedly
China's high﹣speed railways _____ from 9,000 to 29,000 kilometres in the past few years.( )
A.are growingB.were growing
C.will growD.have grown