Can you hear a train? Yes.
19－9＋7＝____
12＋3－4＝____
17＋2－5＝____
10＋6＋2＝____
19－5－2＝____
16＋2－2＝____
□÷△=2……18，△最小是17．
Can you hear a train? Yes.