21. Would you please pass me the book ________ cover is black?
A) which
B) whose
C) that
D) its
22. ________ in the company for three years, Mark has become experienced in business negotiations.
A) Having worked
B) Have been working
C) Have worked
D) Worked
23. Not until she arrived at the meeting room ________ she had forgotten to bring the document.
A) she realized
B) did she realize
C) she did realize
D) does she realize
24. John had never been abroad before, ________ he found the business trip very exciting.
A) because
B) though
C) so
D) while
25. ________ some students are able to find employment after graduation, others will have to return to school and earn an advanced degree.
A) Since
B) While
C) Because
D) If
Section B
Directions: There are 10 incomplete statements here. You should fill in each blank with the proper form of the word given in brackets. Write the word or words in the corresponding space on the Answer Sheet.