is vs was

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Students in the early 1960s were taught that electrons orbit the nucleus of an atom and the path of this orbit was circular.


the path of this orbit was

the path of this orbit is

the path of this orbit has been

that the path of this orbit is

that the path of the orbit was


Ans.Dwhy not E

[scoobydooby]

students were taught x and y. x and y need to be parallel.

x) electrons orbit the nucleus. present tense
y) path of the orbit was nucleus. past tense.

to maintain parallelism, we must keep x and y in the same tense. since x has present tense and is in the non-underlined portion, we must use present tense for y. so "is" is preferred to was. therefore D

[nervesofsteel]

also E changes meaning..
it sounds like... it was taught that path used to be circular.. and is not circular when the lesson was being delivered..........

SO D