Question

Which sentences have incorrect parallel structure? House Un-American Activities Committee The House Un-American Activities Committee (HUAC) was an investigative committee of the U.S. Congress. Created in 1938, the committee investigated questionable activity and if people were disloyal to the United States. During the Cold War, the HUAC became a permanent committee. Its goal was to investigate suspected communists within the U.S. In 1947, the committee held nine days of hearings to investigate communist influence in the Hollywood film industry. The committee believed that some American artists were communists. The list of suspected people became known as the "Hollywood blacklist." One of the most famous hearings held by the HUAC involved Whittaker Chambers and Alger Hiss. Chambers, a senior editor of Time magazine, had once been a member of the Communist Party and a Soviet spy. Chambers testified before the HUAC against Hiss and claiming that Hiss belonged to an underground communist organization. Hiss denied the charges against him, but the committee found him guilty of perjury. The committee was unable to convict him for espionage because the statute of limitations had expired.

Answer 1

Parallel structure means using a similar form or pattern of words to balance sentences.  

This sentence does not have parallel structure:  

Created in 1938, the committee investigated questionable activity and if people were disloyal to the United States.  

The structure should be the same on both sides of the conjunction and, which is not seen with the phrases "questionable activity " and "if people were disloyal to the United States." The sentence should be written this way:  

Created in 1938, the committee investigated questionable activity and people believed to be disloyal to the United States.

The nouns activity and people are now parallel.

This sentence isn't parallel in structure because the verb form is different across the sentence:  

Chambers testified before the HUAC against Hiss and claiming that Hiss belonged to an underground communist organization.  

This sentence can be made parallel if it is written as follows:  

Chambers testified before the HUAC against Hiss and claimed that Hiss belonged to an underground communist organization.  

The verbs testified and claimed are now parallel.

(on Plato)

Answer 2

Chambers testified before the HUAC against Hiss and claiming that Hiss belonged to an underground communist organization.

should be " testified " and " claimed "....so their both past tense