题目

Armed with only a light, some food and a map, the team searched the cave for the dangerous creature. Their leader, well experienced in cave expeditions,   41   (lead) the way. Suddenly he lost his footing and fell into a deep hole. Concerned for the   42  (safe) of their leader, the rest of the team looked down into the hole. Frightened, they turned round to leave the cave, but as they did so they heard   43  strange low noise behind them. They looked round and saw an enormous creature that was   44  tall as a tower.   45 (freeze) with horror, they stood, rooted to the 若小唐同学掷出的铅球在场地上砸出一个直径约为10 cm、深约为2 cm的小坑，则该铅球的直径约为________cm．