Everyone in the office is having lunch at the moment. Explanation: The sentence is in the present continuous tense which requires the verb "to be" in its present tense form "is" followed by the present participle "having."

A million dollars is a big amount of money. Explanation: The subject "a million dollars" is singular, so the verb "to be" should also be singular "is" instead of "be."

A large number of students in this school speak English fluently. Explanation: The subject "a large number of students" is plural, so the verb "speak" should also be plural.

The Old Man and the Sea was written by Hemingway in 1951. Explanation: The sentence is in the past tense, so the verb "to write" should be in its past participle form "written."

Neither Jim nor his friends are studying now. Explanation: The subject "neither Jim nor his friends" is plural, so the verb "to be" should also be plural "are" instead of "is."

Both my sister and I were shocked by what you said. Explanation: The sentence is in the past tense, so the verb "to be" should be in its past tense form "were" instead of "are."

The boy was at the cinema along with his friends yesterday. Explanation: The sentence is in the past tense, so the verb "to be" should be in its past tense form "was" instead of "is."