Over the past few months，Chinese COVID vaccines （疫苗） ________ in many other countries.
A．have arrivedB．arrived
C．will arriveD．had arrived
Though Betty and Lily are twins，Betty isn't so ____________ as Lily．（ ）
A．more outgoingB．most outgoing
C．outgoing
David，look at the man in black over there．Can you tell me ____________？
He is an engineer．（ ）
A．who is heB．who he is
C．what he does
I feel upset because I am too heavy．
____________ do more exercise to lose some weight？（ ）
A．Why don'tB．Why notC．Why not to
Mrs．White，can I leave my homework for tomorrow？
I'm afraid not．Don't ___________what you can do today till tomorrow．（ ）
A．put offB．get offC．take off
Mum，I'm going climbing．Must I clean the room now？
No，you_____________．You can do it this evening．（ ）
A．can'tB．mustn'tC．needn't