1. Word choice: They had professionals who had come from more than 20 companies. The correct word to be used is ‘professionals’ in place of 'professor' as it is more appropriate. Please choose the correct word to express your thought. Use an English dictionary or thesaurus to locate and understand unfamiliar words and phrases and their meanings. 2. Missing word: They had professionals who had come from more than 20 companies. The words 'who had' need to be inserted in this sentence to make the meaning of the sentence complete and clear.