—The poor weather was _________ responsible for the crash.—I’m with you on that. Carelessness was also to blame. 

Bill always seems so self-confident, but _____ he’s extremely shy. 

To understand the grammar of the sentence, you must break it       into parts. 

He was __ twenty when he was gone.

________，the search engine just gave me some brief introductions rather than the whole content of the book to read.