(1) CBA (2) Drainage (3) Too many insoluble impurities in the liquid (4) Evaporation; iodine

Test question analysis: (1 ) C is dissolution, B is filtration, A is evaporation, the correct order of operations is CBA.

So fill in: CBA．

(2) B is for filtration. During filtration, the function of the glass rod is to drain water.

So fill in: drainage.

(3) If there are too many insoluble impurities in the liquid, the filtration rate will be too slow.

So fill in: There are too many insoluble impurities in the liquid.

(4) Drying seawater to obtain coarse salt is a crystallization method that uses evaporation. People can eat seafood to supplement iodine to prevent goiter.

So fill in: evaporation; iodine.

Comments: This question mainly tests knowledge of the steps and methods of purifying coarse salt. It is relatively simple and can be answered correctly by memorizing the textbook content.