She seems like a good friend, but she's actually up to something bad. She wants to secretly sabotage your relationship with your boyfriend so that she can swoop in and win his heart.
 is up to something bad or evil has bad or evil intentions指一個人有不善良的或邪惡的目的
她看起來是個好朋友但其實不懷好意, 她想搞壞妳跟妳男友的關係, 這樣子就可以趁機介入贏得妳男友的喜愛.< >
這是一個連環問題: 燃燒石油導致二氧化碳增加，二氧化碳增加導致溫室效應，溫室效應導致冰層融化、海平面上升。 (請填空)
This is a chain of problems. Burning oil leads to increase in carbon dioxide, which leads to the greehouse effect, which leads to melting of glaciers, which leads to rising sea levels.