Question

in the late 1990s, physical therapists began experimenting with simple resistance tools to treat chronic elbow pain. by 2006, the flexbar ____ widespread clinical adoption, as controlled studies showed that its eccentric twisting exercises reduced symptoms of tennis elbow more effectively than passive stretching alone. as a result, the device became a standard component of rehabilitation programs in sports medicine clinics.
13
which choice completes the text so that it conforms to the conventions of standard english?
a would gain
b had gained
c has gained
d did gain

Explanation:

To determine the correct verb tense, we analyze the time context. The events "began experimenting" (late 1990s) and "by 2006" are key. "By 2006" indicates an action completed before another past action (the studies showing effectiveness and the device becoming standard). The past perfect tense ("had + past participle") is used to show an action completed before a past time or another past action.

• Option A ("would gain") is conditional/future - in - past, not fitting the "by 2006" completion context.
• Option B ("had gained") is past perfect, which correctly shows the FlexBar's gain of adoption was completed by 2006, before the subsequent results (device becoming standard).
• Option C ("has gained") is present perfect, which is inappropriate as the time frame is in the past (by 2006).
• Option D ("did gain") is simple past, which doesn't convey the completion of the action by 2006 relative to other past events.

Answer:

B. had gained