With the help of high technology, more and more new substances ______ in the past years.
A．discoveredB．have discovered
C．had been discoveredD．have been discovered
D
時(shí)態(tài)和語態(tài)。由句中的時(shí)間狀語in the past years可知，空格應(yīng)填現(xiàn)在完成時(shí)；又因句子中的主語new substances與discover為被動(dòng)關(guān)系，故選D項(xiàng)。
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