________ their luggage, the tourists hurried to the airport． Packed。 After packed。 Having packed。 Packing。
The development of the light bulb ________partly as a result of the widespread availability of electricity and the need for cheap, clean light． occurring。 was occurring。 was occurred。 occurred。
It is a small country, yet has a lot of________ resources． potential。 unknown。 secret。 unlimited。
How can he do so much work? He ________ stay late at the office every evening and take work home at weekends． need。 can。 might。 must。
It is often easier to make plans than to ________ them out． put。 carry。 take。 practice。
John________ he could improve his exam results, but he did not have enough time to study．
