若f(x)，g(x)都在[a，b]上可积，且f(x)＜g(x)，则当a＜b时，必有∫a→xf(t)dt可导．(    )

判断题The Letter of credit shall be examined only by the exporter.

判断题Offer and counter-offer are two indispensable steps to reach an agreement.

判断题Acceptance should be declared only by written form.

判断题After the exclusive distributor has purchased the goods, the actual buyer shall open an UC.

判断题The notice of the date of hearing subsequent to the first hearing is also subject to the 30-day or 15-day time limit.