It must be morning, ____ the birds are singing.
举一反三
- It must be morning, ____ the birds are singing. A: for B: because C: as D: since
- The day breaks， __________ the birds are singing.
- The day breaks, _________________ the birds are singing.
- ______ are the birds doing? They are singing in a tree.
- _____are the birds doing? They are singing. A: Who B: What C: How