题目

Directions: For each blank in the following passage there are four words or phrases marked A, B, C and D. Fill in each blank with the word or phrase that best fits the context. The Lipstick Effect Absent During This PandemicWith customers stuck inside their homes, they don't seem to be1to wear or purchase lipstick and instead are stocking up on sheet masks and hand sanitizer (消毒液). This is a change from typical customer behavior, with lipstick sales2 experiencing a boom during economic crisesIn the four years from1929 to1933, industrial production in the United States halved whereas sale如图所示，将两相同的木块a、b置于粗糙的水平地面上，中间用一轻弹簧连接，两侧用细绳固定于墙壁．开始时a、b均静止．弹簧处于伸长状态，两细绳均有拉力，a所受摩擦力Ffa≠0，b所受摩擦力Ffb=0，现将右侧细绳剪断，则剪断瞬间（ ）A．Ffa大小不变B．Ffa方向改变C．Ffb仍然为零D．Ffb方向向右