——Will you go to the picnic this Saturday?
——I'd like to,______ I'll have to help look after my baby sister.
A.but B.or C.and D.so
A
【详解】
句意:——这周六你去野餐吗?——我想去,但是我不得不照看我的妹妹。
A. but但是; B. or或者; C. and 和; D. so所以;根据I'd like to和I'll have to help look after my baby sister.之间是转折关系;故选A