填空题 1.Our mouth is ________.(红色的) 2.This pencil is ________.(绿色的) 3. yellow+blue=________黄色+蓝色=________ 4. ________+black=grey ________+黑色=灰色 5.My ball is red.(对画线部分提问) _______________ is your ball? 6.—Is this her book? (根据问句,写出否定答句) — ________, it isn't.