All guests must at the front desk.
举一反三
- All guests must _____ at the front desk. A: signing in B: sign in C: signed in
- All guests must<br/>() at the front desk. A: signing in B: sign in C: signed in
- All guests must ______ at the front desk. A: signing in B: sign in C: signed in D: be signing in
- All guests must___at the front desk. A: signing in. B: sign in C: signed
- Guests （）sign in at the front desk to enter the building A: can B: may not C: must D: used to