问题 1单词型What is the structure of the present continuous tense?S+am/is/are+verb-ingS+tobe+VingS+tobe+verb-ingSubject+tobe+verb-ingSubject+is/am/are/+verb-ing
问题 5单词型Which word is usually used with the present continuous tense to indicate the time of action?now
问题 13单词型What is the negative form of 'You are studying' in the present continuous tense?You are not studying