单项选择题
A．hardly sees his sister B．sees his sister only at Christmas time C．sees his sister on Jack's birthday D．always sees his sister
A．Scientists consider apes may drive trains some day. B．Apes have worked in some factories. C．Apes may one day be used to gather crops. D．An ape is not a large monkey.
A．Animals are very skillful at a circus. B．They are big and strong. C．Some animals are as clever as human beings. D．Animals can be trained because they like to get something as a rewar