Many of the conditions that population pressures- overcrowding, unemployment, poverty, hunger and illness______ lead to dissatisfaction.

单项选择题To give you a general idea of our products, we enclose the catalogues showing various products handled by us with detailed ______ and means of packing.

单项选择题To survive in the intense trade competition between countries, we must ______ the qualities and varieties of products we make to the world market demand.