While intelligent people can often ________ the complex, a fool is more likely to complicate the simple.
| A．sacrifice | B．substitute | C．simplify | D．survive |
______ is even more important is that the earth cooled down, water began to appear on its surface.
| A．When | B．That | C．Which | D．What |
Jane _____ these families of chimps for many years and helped people understand how much they behave like humans.
| A．had studied | B．studied | C．studies | D．has studied |
It is so wet there _____ the trees are extremely tall, some measuring over 90 meters.
| A．what | B．which | C．that | D．why |
Many _______ of years later, the first extremely small plants began to appear on the surface of the water.
| A．millions | B．million | C．million of | D．millions of |
_______ Jane’s way of studying chimps, our group are all going to visit them in the forest.
| A．Follow | B．Following | C．Followed | D．To follow |