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题目： If $$xyz > 0$$, is $${x}{y}^{2}{z}^{3} < 0$$ ?(1)$$y < 0$$(2)$$x > 0$$

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题目： If a, b, c, and d are positive integers, is $$(\frac {a} {b})(\frac {c} {d}) >\frac {c} {b}$$?(1)$$c > b$$(2)$$a > d$$

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题目： In the triangle above, is $$x >90$$?(1) $${a}^{2}+{b}^{2}<{15}$$(2)$$c > 4$$

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题目： If $${l}_{1} \| {l}_{2}$$ in the figure above, is x = y? (1) $$p\|r$$ and $$r\|t$$ (2) $$q\|s$$

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题目： If $$x > 0$$, then $$\frac1 {\sqrt{2x}+\sqrt{x}}$$ =

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题目： If a and b are positive, is $$(a^{-1}+b^{-1})^{-1}$$ less than $$(a^{-1}*b^{-1})^{-1}$$?(1)$$a = 2b$$(2)$$a + b > 1$$

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题目： If $$\frac{7x} 3+a=8$$ and $$a > 8$$, then, in terms of a, $$\frac{3x} 7=$$

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题目： The table gives three factors to be considered when choosing an Internet service provider and the percent of the 1,200 respondents to a survey who cited that factor as important. If 30 percent of the respondents cited both "user-friendly" and "fast response time," what is the maximum possible number of respondents who cited "bargain prices," but neither "user-friendly" nor "fast response time?"

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题目： If $${x}\neq{0}$$, is $$\frac {x^2} {\mid x\mid}<{1}$$?(1)$$x < 1$$(2)$$x > -1$$

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题目： If u, v, and w are integers, is u > 0 ?(1) $${u}={v}^{2}+{1}$$(2) $${u}={w}^{4}+{1}$$

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题目： The operation $$\Delta$$ is defined for all nonzero x and y by $${x}\Delta{y}={x}+\frac x y$$. If $$a > 0$$, then $$1\Delta (1\Delta a) =$$

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题目： Is $$x > k$$?(1)$${2}^{x}*{2}^{k}={4}$$(2)$${9}^{x}*{3}^{k}={81}$$

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题目： A certain computer program generates a sequence of numbers $${a}_{1}$$, $${a}_{2}$$, ... , $${a}_{n}$$ such that $${a}_{1}={a}_{2}={1}$$ and $${a}_{k}={a}_{k-1}+{2a}_{k-2}$$ for all integers k such that $$3 \le k\le n$$. If $$n > 6$$, then $${a}_{7}=$$ ?

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题目： The "dilemma" mentioned in highlight text can best be characterized as being caused by the necessity to make a choice when faced with a

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题目： Professor Knight has noticed that students who guess on her multiple-choice tests are significantly more likely to choose answer choice C instead of A, B, D, or E. Basing her judgment on the fact that a variety of students from different social groups and backgrounds all do this, she has concluded that this tendency was acquired from her colleague Professor Leigh's habit of predominantly using C as a correct answer choice, rather than students' natural tendency to choose the middle letter. Professors Knight and Leigh are the only professors who give multiple choice tests in the required classes of the first and second year.Which of the following, if true, would most strengthen the conclusion drawn by Professor Knight?