There _____a book and two pencils on the desk.
The chemistry teacher asked the students ________ more attention _________the lab clean.
---- My best friend left me because I hit him on the face last night .----______________ .You were so rude.
---- If you don’t know what the new words mean , ________- in a dictionary .
---- ______ you ever ______ aboard ?--- Yes, but only once.
---Why didn’t the little boy raise his hand in class today ?---- Maybe the questions are ______ difficult for him_______ answer .