[ Gerunds and Infinitives ]
As doctors continue (search) _______ for a cure for the common cold, they have found some things that make people more vulnerable to catching a cold.
A. to search
B. searching
C. to search
D. “to search” and “searching”

Random Topics:
Present Perfect Simple and ContinuousComparison & Modal Verbs in Passive VoiceGrammar and PunctuationVerb + InfinitiveAdverb of TimePhrasal Verbs and Verb FormsInfinitives and ING FormsAdjectives or AdverbsSimple Verb TensesRun-On SentencesOther quiz:
Must or Mus not › ViewWe ______ forget our homework at home.
A. must
B. mustn’t
Simple Past Tense (was/were) › View
There _____ a football match on TV.
A. is
B. was
C. were
D. are
Grammar › ViewShe ________ have short hair, but now it’s long.
A. used to
B. didn’t
C. use to
Grammar › View
I ____ my English homework, but I haven’t done my Spanish homework _____.
A. already do / yet
B. already did / still
C. have already did / still
D. have already done / yet
