据2005年3月9日北京电视台报道：20年来北京空气中二氧化硫含量首次达标，这是
题型：选择题
问题：
据2005年3月9日北京电视台报道：20年来北京空气中二氧化硫含量首次达标，这是市政府实施“煤改气”工程取得的显著成果．“煤改气”中的“气”指的是天然气，其主要成分是（ ）
A．甲烷
B．一氧化碳
C．乙醇
D．氢气
题型：选择题
To discover whether bees can see colors, the following experiment is set up. A table is put in a garden and on the table is a piece of blue cardboard (硬纸板) with a drop of syrup (糖浆) on it. After a short time, bees come to the syrup. The bees then fly to their hive (蜂窝) and give the syrup to other bees in the hive. Then they return to the feeding-place which they have discovered. After a while, the blue cardboard with the syrup on it is taken away. Instead of this card, a blue card is now put on the left side of the first feeding-place and a red card to its right. These new card have no syrup on them. Thus, the blue card is on the left, the red card on the right, and there is nothing where the first blue feeding-card used to be. Very soon bees arrive again, and fly straight to the blue card. None to the red card.
小题1:To do the experiment, altogether how many cards do you need to prepare?
A．Two, one blue and one red.
B．Three, two blue and one red.
C．Three, one blue and two red.
D．Four, two blue and two red.小题2:If figure 1 (图1) below shows the table top during step 1 of the experiment, which picture in figure 2 represents (代表) step 2?
(blue card with syrup blue card red card )
Figure 1:
Figure 2:
A B C D
小题3:During step 2 of the experiment, the bees come to_______.
A．the original blue card with syrup on it
B．the new blue card with no syrup on it
C．the empty space where original blue card was
D．the new blue card with syrup on it小题4:The experiment has proved that bees _______.
A．cannot see colors
B．can see colors
C．cannot see blue
D．cannot see red