One day， _____，Newton saw an apple fall from a tree.
| A．to sum up | B．what’s more | C．it is said | D．in addition |
_______ such heavy pollution already, it may now be too late to clean up the river.
| A．Having suffered | B．Suffering | C．To suffer | D．Suffered |
Robert is said _______ abroad, but I don’t know what country he studied in.
| A．to have studied | B．to study |
| C．to be studying | D．to have been studying |
The purpose of new technologies is to make life easier, _______ it more difficult.
| A．not make | B．not to make | C．not making | D．do not make |
When I got back home I saw a message pinned to the door _______ “Sorry to miss you; will call later.”
| A．read | B．reads | C．to read | D．reading |
European football is played in 80 countries, _______ it the most popular sport in the world.
| A．making | B．makes | C．made | D．to make |