89. ________ the earliest system of writing.
A. The constitution of pictograms
B. Pictograms in the constitution
C. Constitute the pictograms
D. Pictograms constitute
90. At temperatures________ absolute zero, substances possess minimal energy.
A. approach
B. approaches
C. approaching
D. they approach
91. The Earth’s one-year revolution around the Sun changes how________ on one hemisphere or the other.
A. falling sunlight
B. the fall of sunlight
C. sunlight in the fall
D. sunlight falls
92. Though sporadic interest in regional dialects________ for centuries, the first large-scale systematic studies did not take place until the nineteenth century.
A. has existed
B. it existed
C. has it existed
D. existing with it