Fill in the blanks.

Scientists ………………. (are / have / had) finally succeeded in converting blood groups A, B and AB into the universal O group. This breakthrough ……………………. (provide / has provided / provides) tremendous hope for the future. It ……………………… (dissolve / will dissolve / dissolves) the blood group barrier and make transfusion and blood donation simpler. However, patient trials are …………………. (needed / needing / need) before the conversion method can be used in hospitals.

Harry Potter ………………… (is / has / have) some serious competition. Scientists ……………………. (are / have / had) come up with a workable solution for an invisibility cloak. Last year, they ………………….. (figured / have figured / were figuring) out a complex mathematical equation for making objects invisible by blending light around them. Now a group of engineers ……………………. (designed / have designed / are designed) a relatively simple device capable of making objects as big as an airplane simply ……………………………… (disappear / disappearing / disappeared).

Solution

Scientists have finally succeeded in converting blood groups A, B and AB into the universal O group. This breakthrough provides tremendous hope for the future. It will dissolve the blood group barrier and make transfusion and blood donation simpler. However, patient trials are needed before the conversion method can be used in hospitals.

Harry Potter has some serious competition. Scientists have come up with a workable solution for an invisibility cloak. Last year, they figured out a complex mathematical equation for making objects invisible by blending light around them. Now a group of engineers have designed a relatively simple device capable of making objects as big as an airplane simply disappear.