They arrived _______ Beijing on the evening of May 24.
A:at
B:in
C:on
相同的杯子装不同量的水,杯子里水越多,声音越____,杯子里水越少,声音越____,空杯子声音最____。
己知:R、Rˊ、Rˊˊ为H原子或烃基
I. R'CHO+ R"CH2CHO →NaOH溶液 →△
II. RCHO+ →无水HCl