Life on land probably began about 430 million years ago, though it has existed in the water for perhaps as long ago 3,000 million years. When we think of the first life on land, we probably think of strange animals coming out of the oceans, but, in fact, no animals could have been living if plans had not been on land first. Plants had to be on land before animals arrived. They supplied the first land animals with food necessary to live, since they are the only form of life that is able to get and store energy.
The first plants to exist out of the water were probably certain kinds of algae(海藻) which were followed by other plants that grew close to the ground near water and needed water in which to reproduce. Once the move to land had been made, however, evolution(进化) took place quickly. By the end of 100 million years, plants had developed their roots, and some developed tall tree-like forms, since height was very important in competing for sunlight. About 300 million years ago, much of the world was covered with forests of huge trees. In most ways they were like modern trees. They had roots, leaves, wood, but mostly they had not developed seeds.

53.Plants with roots appeared about_______ million years ago.
A.430 B.300 C. 330 D. 100

56.Which of the following is true?
A．Algae have existed for more than 430 million years.
B．It is impossible that algae might be the earliest plant on land.
C．Plants get food from animals in the oceans.
D．Evolution began after animals appeared on land.

About 300 million years ago, much of the world was covered with forests of huge trees.从这句知道，植物生根在这个前面，所以，前面说的100 million是以430为起点说的，从而得出植物生根从430时已经过去了100，所以选C，330

Life on land probably began about 430 million years ago和Once the move to land had been made, however, evolution(进化) took place quickly说明动物是由algae进化的，进化的过程中不断向 land上move，所以 选A