[ Causative Verb ]
No clinical studies —- in this child disease research so far.
A. Had completed
B. Will be completed
C. Have completed
D. Have been completed

Random Topics:
Grammar and Passive VoiceContractions and ConjunctionsRoot WordBe Going To vs. WillCommon & Proper Nouns3rd Person SingularModals VerbPresent and Past Perfect TensesConditional Type 1ConnectorsOther quiz:
Present Simple › ViewAlice …….. her homework after school.
A. does
B. do
C. doesn’t
D. don’t
Grammar › View
Having a positive attitude helps you to _____ a challenge.
A. face
B. progress
C. shoulder
Grammar › ViewI’m addicted……….these sweets. I love them!
A. at
B. on
C. to
Grammar › View
What do restrictive clauses do?
A. Limit or define the noun or pronoun
B. Connect adjectives to nouns
C. Express a complete thought
D. Provide additional information