选词填空，将方框中单词的合适形式填在横线上。（5分）

小题1:Dogs are ___________( 诚实的 )friends of human beings. 

小题2:I felt so happy because my father ____  _ ( 答应 ) to buy me a new cellphone.

小题3:Please tell me the____________（原因）why you are late.

小题4:Would you give me some bread? I am so ___________( 饥饿  ) .

小题5:Who can give this question a  ________（正确的）answer?

精刮刀和细刮刀的切削刃都呈圆弧形，但精刮刀的圆弧半径较大。