单项选择题 A tonnage tax is levied according to the（）.

单项选择题 A quite simple method of improving a berth’s capacity is（）.

单项选择题 A promise to pay pro rata freight will be（）merely from acceptance of the goods at an intermediate port where the master insisted on leaving it，or from acceptance of the proceeds of the sale where the master has exercised his discretion to sell the goods in the interest of the cargo-owners.