单选题 We ______ our breakfast when an old man came to the door.

单选题 His intelligence and experience will enable him to ______ the complicated situation.

单选题 I appreciate ______ to your birthday party at the restaurant.

单选题 An investigation was made into the accident ______ fifty people were killed.

单选题 The ______ of new scientific discoveries to industrial production methods usually makes jobs easier to do.

单选题 ______ such a good chance, he planned to learn more.

单选题 Although this area is very poor now, its ______ wealth is great.

单选题 Tom's leg got hurt ______ the Purple Mountains.

单选题 The man to whom we handed the forms pointed out that they had not been ______ filled in.