She locked her room _____ a thief would break into it

Have you invited Alice to our party?—Yes. But she _____ come; she is busy nowadays.

Bob likes the camera very much because it can be _______ to take pictures in cloudy or sunny conditions.[ ]

Not only the young but also the old are getting interested _______Wechat.—They can communicate more freely.

Raymond’s parents wanted him to have_______ possible education.