[ Modal Verbs ]
Scientists fear that a patient’s immune system _____ stem cells unless they _____ genetically identical to the patient’s other cells.
A. may reject / are
B. may have rejected / were
C. could reject / had been
D. has rejected / has been
E. would be rejected / were
Select your answer:
Random Topics:
If vs. Unless Cleanup vs. Clean UpHomonyms Grammar - much, many, a lot ofPast Continuous and Past Simple TenseDirect Object and Indirect ObjectGrammar (want to/ need to/ have to)Present & Past TensesPerfect Tenses and Vocabulary
Other quiz:
Should / Should not › ViewThe word should is used to recommend ____________ ideas
A. good
B. bad
C. interesting
D. surprising
Grammar › View
Which of the sentences is a compound sentence?
A. Basketball and soccer are my favorite sports.
B. Valentine’s Day is on February 14th, and St. Patrick’s Day is on March 17th.
How to use : Read the question carefully, then select one of the answers button.