托业考试

【单选题】Guests ______ sign in at the front desk to enter the building.
A、can
B、may not
C、must
D、used to

网考网参考答案：C
网考网解析：
暂无解析 document.getElementById("warp").style.display="none"; document.getElementById("content").style.display="block"; 查看试题解析出处>>