GMAT sentence correction – How do I start prep?

Direction: Identify the subjects and verbs

Sample answer: 1. Industry, Which(subject) – has (verb)

The $10.7 billion ski and snowboarding industry, which has centers in 38 states and employs 187,000 people directly or indirectly, lost, between 2000 and 2010,  $1.07 billion in revenue, owing to the warming trend that forces half the nation's ski areas to open late and almost half to close early.

Direction: Identify the subjects and verbs

Schistosomiasis, a disease caused by a parasitic worm, is prevalent in hot, humid climates, and it has become more widespread as irrigation projects have enlarged the habitat of the freshwater snails that are the parasite’s hosts for part of its life cycle.

Direction: Identify the subjects and verbs

After a long difficult struggle leading up to the 1984 Democratic Presidential Primary, Walter Mondale consolidated his lead for the nomination, but he won only 13 electoral votes in the general election.

Direction: Identify the subjects and verbs

The more cautious commanders of the Army of the Potomac, such as George McClellan and George Meade, chose to withdraw after costly battles, but commander Ulysses Grant’s strategy was to keep up pressure on Lee’s Confederates even after losing a battle to them, and then to occupy positions between Lee’s army and Richmond to invite another open battle.

Directions: Identify the subjects and verbs

Getting adequate sleep, a full eight hours every night, the depth of which will be enhanced by a regular regimen of physical exercise, has significant consequences not only for one’s immediate short term health, but also for the immune system’s ability to fight major illness over the long term.