48×25
=(40＋8)×25
=40×25＋8×25
=1200
在人体内，都是因为缺乏激素而引起的一组疾病是（ ）
①呆小症 ②糖尿病 ③侏儒症 ④白化病 ⑤镰刀型贫血症 ⑥夜盲症．
看图，阅读短文，判断正误。
Tommy is a boy. He is apupil. He is a short and thin. He is ten. He gets up early every morning. He gets up at half past six. He brushes his teeth at a quarter to seven in the morning. He goes to school at half past seven in the morning.
He gets up early every morning. He gets up at half past six. 
He brushes his teeth at a quarter to seven in the morning. 
He goes to school at half past seven in the morning. 