Thinking of solving problems: according to life experience and understanding of quality unit and data size, it is known that a math book weighs about 200 grams; A cake weighs 90 grams; A basket of apples weighs 20 kilograms; A basketball weighs 650 grams; This leads to a solution.

A math book weighs about 200 grams; A cake weighs 90 grams;

A basket of apples weighs 20 kilograms; A basketball weighs 650;

So the answer is: grams, grams, kilograms, grams.

, 1, fill in the appropriate units in the horizontal line.

A math book weighs about 200 _ _ _ _ _ _; A piece of cake weighs 90 _ _ _ _ _ _;

A basket of apples weighs 20 _ _ _ _ _ _; A basketball weighs 650 _ _ _ _.