二甲苯和浓硫酸在一定温度下可发生（）反不。
参考答案：磺化
--- Where is Mr. Smith? --- He ________ Guangzhou. He ________ there for a week.
A．has gone to; has been to
B．has gone to; has been
C．has been to; has gone to
D．has been in; has gone to
心理健康的标准（）。
