Question

In the past twenty decades, no new antibiotic--------discovered to manage rabonella infection among adults.
a. have
b. has been
c. had
d.has​

Answer 1

The given blank can be filled as such: In the past twenty decades, no new antibiotic has been discovered to manage Rubella infection among adults.

What is the use of has in a sentence?

• Has, had and have are all used in perfect tenses.
• With these, it is necessary to use the third form of a verb.

• There are three different types of perfect tenses.

• Their names are present, past and future tense.

• The verb used in these sentences is called the auxiliary verb.
  

Answer 2

The following sentence can be used to fill in the blank: No new antibiotic has been identified to treat Rubella infection in adults in the last two decades.

What is the use of has in a sentence?

• Has, had, and have are all used in perfect tenses.

• With these, it is necessary to use the third form of a verb.

• There are three different types of perfect tenses.

• Their names are present, past, and future tense.

• The verb used in these sentences is called the auxiliary verb.

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