When I try to understand ________ that prevents so many children from being happy, there seem to be three causes.
| A．why it is | B．what it does | C．why it does | D．what it is |
---How can you_____them_____the solar cars?
---Solar cars are getting better all the time.
| A．persuade,to use | B．persuade,into using | C．persuade,in using | D．persuade,for using |
Indeed,thanks to the good ideas of lots of people,like the cycling fans in the 1960s,many people around the world______the city centre streets without cars for many years.
| A．have enjoyed | B．enjoyed | C．have been enjoying | D．have been enjoyed |
_______a bicycle to use,you have to insert a special card.
| A．Taking | B．To take | C．For taking. | D．Taken. |
Camp Xtreme is the biggest adventure camp in Scotland and has 15_____staff.
| A．good training | B．good trained | C．well trained | D．well training |
Marco______his tales though few people at that time believed it to be true.
| A．stood up | B．stood by | C．stood on | D．stood to |