They _________ their service up to now.
Đáp án B
Trong câu có trạng ngữ thời gian “up to now” (cho đến bây giờ) nên ta chia động từ ở thì hiện tại hoàn thành.
Which of the followings is NOT an evidence of monitoring studying?
It can be a very (30) __________ surprise if you expect to shake hands and get a kiss or a hug instead.
According to the passage, what can be learnt about passive students?
Which of the followings is NOT badly affected by contaminated groundwater?
Which of the followings is the flow of water from the ground to the surface?