as

[tankobe]

1#
as stephen initially believed, the two popular arthritis drugs are possibly not safe.
as stephen has believed, the two popular arthritis drugs are possibly not safe.

2#
as initially believed, the two popular arthritis drugs are possibly not safe.
as was initially believed, the two popular arthritis drugs are possibly not safe.
as has been believed traditionally, the two popular arthritis drugs are possibly not safe.

3#
as it was initially believed, the two popular arthritis drugs are possibly not safe.
as it has been believed traditionally, the two popular arthritis drugs are possibly not safe.

there are three groups of sentences. Athough having seen some of grounp 1# and 2# in GMAT, i has nerver seen 3#. is grounp 3# ok？

[StaceyKoprince]

Please read (and follow!) forum guidelines when posting. This folder is for high-level strategic questions about the GMAT. Questions such as the one above should be posted in the General Verbal Questions folder.

The short answer to your question is "no" - the sentences in group 3 are not written correctly. They should not include the pronoun "it." If you'd like to discuss further, please post your question in the General Verbal Questions folder. Thanks!

[tankobe]

Please read (and follow!) forum guidelines when posting. This folder is for high-level strategic questions about the GMAT. Questions such as the one above should be posted in the General Verbal Questions folder.

The short answer to your question is "no" - the sentences in group 3 are not written correctly. They should not include the pronoun "it." If you'd like to discuss further, please post your question in the General Verbal Questions folder. Thanks!

sorry, stacey! i know the rule. i am afraid that i was too tired to make a mistake when i posted, and next time, i will be careful. [so every intructor can move this thread to the supposed sub-forum]
by the way, your short answer is ok enough to do me a favor.

[StaceyKoprince]

Thanks for responding! :)