13.（ ）

(单选题)______ is the application of linguistic theories and princip (单选题)I found ______ difficult to fall asleep after seeing this ho (单选题)China ______ 56 ethnic groups. (单选题)We passed areas of open grassland on which a flock of ______ (单选题)Nowadays pets ______ as family members by many people. (单选题)The play is neither as interesting ______ as attractive as w (单选题)The locals here are all very hospitable so ______ people in (单选题)There ______ a watermelon and several apples in the basket. (单选题)I have read ______ of these books since last year. (单选题)We should always keep it in mind that ______ selfish we are,