1. My mother has made the doll.

2. The doll has been made by my mother.

3. The doll is made by my mother.

4. The doll was made by my mother.

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Is #2 the passive sentence of #1? What about #3? Can #3 be the passive of #1?

#4 is the passive of #1, #2 or #3 are not.

To write Haz's answer correctly:

#4 is the passive of #1.
#2 and #3 are not.

Yes, sentence #2, "The doll has been made by my mother," is the passive sentence form of sentence #1, "My mother has made the doll." In the passive voice, the subject of the sentence receives the action rather than performing it. Therefore, in sentence #2, the doll is the subject receiving the action of being made by my mother.

On the other hand, sentence #3, "The doll is made by my mother," is not the passive form of sentence #1. Sentence #3 is a simple present tense sentence stating a general fact or a habitual action. The verb "is made" in sentence #3 is in the present tense, describing an action that regularly happens or is true in general. In this case, it does not focus on who is performing the action but rather on the fact that the doll is made by my mother. To form a passive construction of sentence #1, you would say, "The doll was made by my mother," as seen in sentence #4.