Acartravelsatarateof50milesperhour.Howlongwillittaketotravel300miles?

Mymother'sworkis_____(make)ourcitysafe.

()“CanIhelpyou?”“I'dlike______bagsofrice.”

阅读理解，根据短文内容判断正(T)误(F)。

It'sSundaymorning.ThestudentsofClass3aregivingtheirclassroomagoodcleaning.

MissHuang,theirteacher,isworkingwiththem.Thechildrenarebusy.Somearecarryingwater;

somearecleaningthewindows;othersaresweepingthefloor.ZhangHuaisputtingupamaponthe

wall.ItisamapofChina.WangFeiandWeiQingaremendingsomebrokenchairs.Thechildrenare.

listeningtotheradiowhiletheyareworking.Theclassroomlooksniceandbrightafterthecleaning.

Thechildrenareveryhappy.Theygohomeforlunchatnoon.

()1.ThechildrenareplayingintheirclassroomonSundaymorning.

()2.MissHuang,theirmother,isworkingwiththem.

()3.ThereisamapofChinaonthewall.

()4.Twoofthemarerepairingthebrokenchairs.

()5.Theyaresingingwhiletheyareworking.

防御素是一类具有抗菌活性的蛋白质，广泛存在于动物体中。有关说法错误的是