Questions 66-70    The greenhouse effect occurs ______ heat from the sun is trapped in theEarth’s atmosphere. ______ heat causes increases in global temperatures,directly affecting animal food sources and habitats. The greenhouse effect isdirectly linked to global warming. Causes of global warming include burningfossil fuels, volcanic eruptions and sunspots. Many changes attributed to thegreenhouse effect cause a ripple effect, with the impact starting on smallerspecies and ______ reaching larger species, like humans. Increasingtemperatures cause an increase in global water temperature. Algae are ______to water temperature increases. When temperatures rise, algae die. Small fishdepend on algae as a food source. ______ an abundant supply of algae, smallfish die or move to another location. Small fish are a direct source of food forlarger fish； thus warming waters cause a ripple effect in the food chain,eventually leading to fewer fish and a reduced food supply for animals,
【題組】66.
(A) which
(B) where
(C) that
(D) when