Fill in the blanks with suitable words according to the meanings in the brackets. 1. His father used to be a ________ (high in rank or position) officer in the Liberation War. 2. Before the speaker began the lecture, he gave a ________ (a movement of hand as part of communication) for everyone to become quiet. 3. I was given some ________ (help) in coming to my decision. 4. He said nothing, but his facial ________ (a look on one's face that communicates feeling) told us everything. 5. _______ in class is the key to efficient(有效率的)study. (thinking deeply about something)