A is correct, the principle of left object and right code, the pointer is biased to the left, indicating that the measured object has been placed when it is not placed on the left. After the balance of the weight is released, the weight of the weight is equal to the sum of the measured object and the weight shifted to the left. So the result is too big.

B correct. The balance is adjusted before returning to zero. Then the reading will add the cursor reading to the wrong place, and the result will be too great.

C is correct. If it is 10g, the weight of 10g is just right, but the weight is worn out, and it is less than 10g. You will continue to add weight or adjust the swimming code, but the reading is still calculated according to 10g, so it is too big.

D error. To the right, according to the straight line principle of light, you should read 2, and you will read a value less than 2, which is obviously too small.