what is the correct verb of the sentence "Be sure there(is,are)no erasures on the thesis.

Answer 1

Which word is the subject of the sentence? Once you know that, you'll choose the verb correctly.

http://grammar.ccc.commnet.edu/grammar/sv_agr.htm
and
http://grammar.ccc.commnet.edu/grammar/subjects.htm#inversion

Let us know what you think.