Now a patent can also write two independent rights?

Both questions will do. For example, you can protect an advanced automobile engine with the priority of 1. Of course, you can request to protect the car made of this engine in the same application. (An automobile using the engine according to claim 1, characterized in that: . . ) if the engine is creative, the car must be creative, and the two independent claims are also unitary.

Of course, you can also understand the law in this way. If neither of the two ways you say is allowed, there is no need to stipulate the singularity rule in Chapter 6 of Part II of the Review Guide.

As for writing, the question 1 has already been mentioned (that is, the example of an automobile engine)

The writing of question 2. 1, an engine, characterized in that (its specific structure)

2. The method for manufacturing an engine according to claim 1, wherein (step)

3. The engine according to claim 1 is used in an automobile.