Oracle9i extends the cursor sharing functionality with the new value of SIMILAR for the CURSOR_SHARING parameter. With CURSOR_SHARING = SIMILAR， cursors are shared for safe literals only. What is meant by ‘safe literals only’？（） ["No literal value is substituted for a shared cursor. ","Different execution plans are generated for substituted literal values. ","The substitution of a literal value will produce different execution plans. ","The substitution of any literal value will produce exactly the same execution plan."]
汽车车身向后倾斜1°～2°，可以降低汽车的空气阻力。
开切眼是沿采煤工作面的（）掘进的。 ["开采线","始采线","终采线"]
能阻滞Na+、K+和Ca2+通道的药物是（） ["利多卡因","维拉帕米","苯妥英钠","奎尼丁","普萘洛尔"]
汽车行驶时滚动阻力、空气阻力、上坡阻力和加速阻力是在任何行驶条件下均存在。
按材料分管子分几种？
