In the lecture, the professor introduces two types of...
First, ...which means..., the example is...
Second, ...which means..., the example is...
另外一种是实验型,模板句可稍作改动:
In the lecture, the professor introduces the theory of...
He / She uses an experiment to explain the theory.
In the first group, ...
In the second group, ...
Sample answer:
In the lecture, the professor introduces two types of way that carnivorous plants catch insects to intake nutrition. First, active way, which means the plants attract insects by secreting something of their own. The example is Venus flytrap can secrete something sweat to attract insects to fly into its mouth and digest them. Second, passive way, which means plants have something to glue insects and eat them. The example is sundew plant has special leaves with little hairs. The hairs secrete sticky glue to trap insects and digest them.