___ there are living creatures in the outer space as those on Earth hasn’t been proved until now.
| A．How | B．When | C．Where | D．Whether |
With so many orphans _______, the charity organization calls for more donations.
| A．to look after | B．being looked after | C．to be looked after | D．looked after |
Welcome to the Science Museum, everyone! This stone axe _______ in South Africa and
experts can’t be exactly sure about its use.
| A．had been found | B．was found | C．has been found | D．would be found |
Some biologists believe this is an ancient survival strategy, _______ a diet with 30 percent
fewer calories than usual increased life span.
| A．for which | B．to which | C．of which | D．in which |
The county, ________ in the north of Shanxi, has a history of more than 1,400 years.
| A．located | B．to be located | C．being located | D．locating |