Questions 11 to 18 are based on the conversation you have just heard.

A．The hydrochloric acid broke the carbon bonds in the carbon dioxide,
B．The magnesium oxide broke the carbon oxygen bonds in the carbon dioxide.
C．The burning magnesium broke the carbon oxygen bonds in the carbon dioxide.
D．The gas collection method broke the carbon - oxygen bonds in the carbon dioxide.

A．Because children could learn skills such as counting, reading from experience.
B．Because children could learn something useful from direct experience.
C．Because parents taught their children in the "Three R’s".
D．Because children taught one another in controlled groups.