Billy has difficulty ______________the rest of the class.
Billy has difficulty ______________the rest of the class.
A.to keep up with
B.to keep up
C.keeping up with
D.keeping on
正确答案是C
扫描二维码免费使用微信小程序搜题/刷题/查看解析。
版权声明：本文由翰林刷题小程序授权发布，如需转载请注明出处。