How long ________ they ________ (dig) the ditch?
have … been digging
暂无解析
Ishallneverforget________(meet)thelatePremierZhouduringhisinspectionofourfactory.
Howlong________they________(dig)theditch?
You________gonow.It’sgettinglate.
Ipreferthisdiagram________thatone.
Wooddoesnotconductelectricity;________.