answer:正确的动词形式是 a. vio，因为这个句子描述的是一个突然发生的过去事件。

answer:Extinction events mark significant changes in Earth's ecology, leading to the end of dominant species and the rise of new ones. These events often define the boundaries between periods on the geologic time scale. Additionally, geological formations provide evidence of past environments and events, such as changes in sea level or volcanic activity. These formations help scientists understand the conditions that existed during different periods of Earth's history and contribute to the划分 of the geologic time scale.

answer:To find the product, perform element-wise multiplication of corresponding entries from both vectors, which results in a new vector with the same number of elements as the row vector. Product Vector: left( begin{array}{c} left(-frac{9}{4}right) cdot left(-frac{1}{2}right) left(frac{9}{4}right) cdot left(-frac{1}{2}right) -1 cdot left(-frac{1}{2}right) left(-frac{5}{2}right) cdot left(-frac{1}{2}right) 2 cdot left(-frac{1}{2}right) end{array} right) = left( begin{array}{c} frac{9}{8} -frac{9}{8} frac{1}{2} frac{5}{4} -1 end{array} right)

answer:According to Gay-Lussac's law, the pressure of a gas is directly proportional to its temperature when the volume is held constant. Therefore, if the temperature of the gas increases, the pressure will also increase because the gas molecules will collide with the walls of the container more frequently and with greater force.