28. Every few years, the coal workers their lungs X-rayed to ensure their health.(A)are having (B) h

問題詳情

28. Every few years, the coal workers their lungs X-rayed to ensure their health.
(A)are having
(B) have
(C) have had
(D)had had

答案：B
難度：適中0.5
統計：A(0),B(0),C(0),D(0),E(0)