单项选择题
A．picking.., in the mountains
B．picking... on the mountain
C．having picked... from the mountains
D．picking... from the mountains
单项选择题 I see four kinds of pressure working on college students today: economic pressure, parental pressure, peer pressure, but self-induced pressure（）.
单项选择题 The traffic police stopped three trucks heavily loading with merchandise that looked as grain bags（）.
单项选择题 Only individual benefactors and ad hoc grants have made possible the ecological surveys already undertaken（）.