This energy allowed the water 24 into the air, which looked just like sneezing!
答案：(B) to jump
【句型】allow + O + to V 固定句型「允許/使某物做某事」；jump（原形動詞，allow的補語結構需要不定詞）、jumping（現在分詞）、jumped（過去式）都不合。
你國中學過 let me go、make me cry——這兩個動詞後面接的是原形動詞，所以看到 allow the water ___ 很容易也填原形 jump。但這一組動詞其實分成兩派：let、make、have 後面接原形動詞；allow、permit、enable、force 後面要接不定詞 to V。 中文都翻成「讓、使」，英文卻不同，這是最常錯的地方。
句子是 This energy allowed the water ___ into the air（這股能量使水滴 ___ 到空中）。動詞是 allowed，句型固定為 allow ＋ 受詞 ＋ to V，所以填 to jump。可以用你熟的句子互相對照著記：Let me go.（原形）／My parents don't allow me to stay out late.（要加 to）——同樣是「讓我做某事」，動詞不同，後面就不同。
jump 是原形，符合 let／make 的句型但不符合 allow；jumping 是現在分詞，allow 的受詞補語不用分詞；jumped 是過去式或過去分詞，放在受詞後面會變成被動語意，但水滴是自己跳起來的。
allow sb／sth to V（允許、使……做某事）、permit sb to V（准許某人做……）、enable sb to V（使某人能夠……）、force sb to V（迫使某人……）、let sb V（讓某人做，接原形）、make sb V（使某人做，接原形）。
When a person sneezes, the droplets can spread diseases. Now research shows that plants have a somewhat 21 problem. Plant diseases can also spread through tiny water drops that jump off leaves— a plant's version of a sneeze. Scientists already knew earlier that wind and splashes of rainwater can move bacteria and other germs from leaf to leaf.
22 other possible transmission routes, researchers at Virginia Tech observed water drops on the leaves of wheat plants that were infected with leaf rust. They found that the sick plants could "sneeze" and 23 tiny water drops filled with leaf rust germs, spreading the disease to neighboring plants. The researchers noticed that small drops of water on the wheat leaves would move to combine and form a larger drop. As they were moving, the energy of the droplets in motion would be released. This energy allowed the water 24 into the air, which looked just like sneezing!
However, not all plants can sneeze. The ability is 25 to those with leaves that are hydrophobic, or repel water—a special feature that forces the liquid to move away when the leaf is exposed to it.