1. Because A and B are int variables and H is float variables, the result of a/b is float. If you want to assign values to each other, you must first unify them into variables of the same type.

2. "h = (float) a/b" here means that the result of dividing plastic variable A by plastic variable B is forcibly converted into float type, and this value is assigned to H. This is not a statement. The statement has already been said, so there is no need to repeat it. Forced conversion is just this format: variable = (the expression on the right or the data type to which the variable is converted) variable or expression;

3.float can be changed to double here, because the number set of double contains float. If the result of a/b is converted to double but it is still within the range of float, it is ok, but it will not work if it exceeds it.

4. For example, char a =' b (variable A is of type char and its value is' b').

byte c =(byte)a； (We want to assign the value of A to C, but A is of char type, so we need to convert the data type of A into.

Byte types like a to achieve assignment),

I wrote a lot, but I didn't make it clear. I hope I can help you. You'd better read the examples in the book yourself and ask the teacher. It is estimated that your harvest will be even greater!